The present invention relates to a communication apparatus which is provided with a call control function (e.g., the call control function of VoIP (Voice over Internet Protocol) to realize voice communications through a computer communication network such as IP (Internet Protocol) network.
There has been proposed the VoIP communication system which realizes the voice communications through the IP network such as an internet telephone system.
In the VoIP communication system described in Japanese Patent Laid-open Publication No. 2003-18182, for example, either the VoIP communication apparatus accommodating a voice communication apparatus on a call-initiate side or an IP telephone set on a call-initiate side converts the call originating telephone number into an IP address, and transfers a call control messages using an IF packet with either a VoIP communication apparatus accommodating a voice communication apparatus on a call-present side having that IP address or an IP telephone set on a call-present side, so that a call is connected by performing the call controlling procedure. In another conventional VoIP communication system, on the other hand, a server (e.g., a call agent or a gate keeper), which manages a VoIP communication apparatus accommodating a voice communication apparatus on the call-initiate side, a VoIP communication apparatus accommodating an IP telephone set and a voice communication apparatus on a call-present side, and an IP telephone set, receives the originating telephone number of a call from that VoIP communication apparatus and converts that telephone number into an IP address, and exchanges the call control messages using the IP packet, with either the VoIP communication apparatus accommodating the voice communication apparatus having that IP address on the call-present side or the IP telephone set on the call-present side, so that a call is connected by performing the call controlling procedure.